enhanced for loop with multiple iteration variables
Alan Snyder
javalists at cbfiddle.com
Fri Dec 21 02:19:14 UTC 2018
RIght, but I don’t see that as a general solution.
Its also a bit kludgy, like saying that methods need only one parameter because you can always pass a data object.
> On Dec 20, 2018, at 2:50 PM, Brian Goetz <brian.goetz at oracle.com> wrote:
>
> For Map, you can do:
>
> for (Map.Entry<K,V> e : map.entrySet()) { ... }
>
> and you're already there.
>
>
>
> On 12/19/2018 9:54 AM, Alan Snyder wrote:
>> Has any consideration been given to supporting iterators that provide more than one iteration variable in the enhanced for loop?
>>
>> Obvious uses would be maps (keys and values) and lists (indexes and values).
>>
>> I have in mind keeping the syntactic sugar approach by using one or more extensions of the Iterator/Iterable interfaces, such as, for example:
>>
>> interface Iterator2<E1,E2> extends Iterator<E1> {
>> E2 get2();
>> }
>>
>> with the extra methods providing the values for the extra variables (associated with the previous call to next).
>>
>> Extending interfaces is not required, but it makes the trailing variables optional, which might be useful. For example, the same iterator could provide values or values and keys.
>>
>> The fact that this approach only works for a fixed set of numbers of variables does not bother me unduly.
>>
>> Alan
>>
>
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